When snorkeling, a diver normally retains the mouthpiece in his mouth while keeping the upper end of the snorkel tube above the water surface to enable him to inhale fresh air through the snorkel and to exhale out through the snorkel. The most common prior art type snorkels had a mouthpiece connected to a relatively long snorkel tube by a U-shaped tubular section. Any water or saliva which may find its way into this prior art type snorkel will drain to the lowest point in the snorkel tube, i.e., the bottom of the U-shaped section, and unless the passageway through the tube becomes completely filled by this liquid, fresh air will be drawn across the surface of the liquid when the diver inhales. Even if a short length of the U-shaped section is completely filled with the liquid, it is still possible for the diver to breath through the snorkel. However, breathing across or through a body of liquid trapped in the snorkel tube is at best an annoyance, and it is particularly annoying to the novice or infrequent snorkeler.
When a snorkeler dives below the surface, the snorkel will be completely filled with water and cannot be used for breathing until it has been cleared of the water. The most common method of "clearing" a snorkel is for the diver to lift the open end of the snorkel above the surface and then to blow sharply into the mouthpiece to force the water of the snorkel. Ordinarily, the diver maintains his face in the water while clearing the snorkel. It is well known to provide a drain port in the wall of the snorkel tube and to mount a one-way valve across the drain port to automatically drain water from the snorkel as the diver comes to the surface and the open end of the snorkel is raised above the surface. In the many different self-draining snorkels which have been designed and marketed, the drain ports have been connected to the main snorkel tube at locations above the mouthpiece, below the mouthpiece, and about level with the mouthpiece. It is also known in the prior art to connect the mouthpiece to an intermediate location on a snorkel tube having a one-way valve at the bottom and an open end at the top. In the latter type of snorkel water which splashed into the snorkel tube drained past the mouthpiece tube into the bottom of the snorkel tube. Such sorkels are more difficult to clear than are the simple non-draining snorkels, but they have the advantage of keeping the breathing passageway relatively clear of water or other liquid.